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Re: For any numbers a and b, ab= a + b - ab. If ab=0, which of
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25 Jul 2012, 00:40

asax wrote:

Can someone pls edit the question.? i was wondering where i was going wrong thinking. question was ab=a+b-ab => 2ab=a+b. and then saw bunuel's reply then understood what the question was!

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Re: For any numbers a and b, a#b=a + b - ab. If a#b=0, which of
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11 Apr 2013, 04:15

Stiv wrote:

For any numbers a and b, a#b=a + b - ab. If a#b=0, which of the following CANNOT be a value of b?

A. 2B. 1C. 0D. -1E. -3/2

------------------------------------------for me the fastest way must be the use of answer choices to find the value of a if a will be an integer after putting the value of of b as given in the answer choices then the answer will be correct with no cumbersome calculations & its fast too ....!! _________________

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Re: For any numbers a and b, a#b=a + b - ab. If a#b=0, which of
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18 Mar 2018, 16:45

1

Hi All,

This is an example of a Symbolism question (and you'll likely see 1 on Test Day). The idea is that you'll be given a "made up" math symbol, told what it "means" mathematically and then asked to solve some minor equation.

Here, we're told to substitute values in for A and B so that the equation….

A + B - AB = 0

We're asked which of the following answers CANNOT be the value of B? So 4 of the answers are POSSIBLE and one is IMPOSSIBLE. There are a couple of ways to approach this prompt. You could work mathematically or you can TEST THE ANSWERS. I'm going to use the answers to my advantage and find the 4 that are possible solutions and the one the creates an impossible situation:

If B = 2, then we'd have... A + 2 - 2A = 0 2 = A So B COULD be 2

If B = 1, then we'd have… A + 1 - A = 0 1 = 0??????? B CANNOT equal 1

At this point, we could stop. I'll show you why the other answers are possible though:

If B = 0, then we'd have… A + 0 - 0 = 0 0 = A So B COULD be 0

If B = -1, then we'd have… A -1 -(-1)(A) = 0 2A = 1 1/2 = A So B COULD be -1

For any numbers a and b, a#b=a + b - ab. If a#b=0, which of
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30 Oct 2018, 00:35

Stiv wrote:

For any numbers a and b, a#b=a + b - ab. If a#b=0, which of the following CANNOT be a value of b?

A. 2B. 1C. 0D. -1E. -3/2

Given:a # b = a + b – ab. and a # b = 0

i.e. a + b – ab = 0

(Adding 1 and subtracting 1 simultaneously in the left part of the equation)

i.e. a + b - ab -1 +1 = 0

i.e. a(1-b) -1 (1-b) = -1

i.e. (a-1)*(1-b) = -1

i.e. (a-1)*(b-1) = 1

i.e. either a = 0 and b = 0or a = 2 and b = 2or (a, b) = (3, 3/2) in any order etc.

Point to be Noted:for \((a-1)*(b-1) = 1\)to be true none of the parts of equation can be zero i.e. (a-1)≠0 as well as (b-1)≠0i.e. a and b can NOT be 1

Answer: Option B
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